/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.io.gcp.bigquery;



import com.bff.gaia.unified.sdk.transforms.DoFn;

import com.bff.gaia.unified.sdk.transforms.windowing.BoundedWindow;

import com.bff.gaia.unified.sdk.values.KV;

import com.bff.gaia.unified.sdk.values.ShardedKey;



import java.io.IOException;

import java.util.concurrent.ThreadLocalRandom;



/**

 * Given a write to a specific table, assign that to one of the {@link

 * GenerateShardedTable#numShards} keys assigned to that table.

 */

class GenerateShardedTable<ElementT>

    extends DoFn<KV<TableDestination, ElementT>, KV<ShardedKey<String>, ElementT>> {

  private final int numShards;



  GenerateShardedTable(int numShards) {

    this.numShards = numShards;

  }



  @ProcessElement

  public void processElement(ProcessContext context, BoundedWindow window) throws IOException {

    ThreadLocalRandom randomGenerator = ThreadLocalRandom.current();

    // We output on keys 0-numShards.

    String tableSpec = context.element().getKey().getTableSpec();

    context.output(

        KV.of(

            ShardedKey.of(tableSpec, randomGenerator.nextInt(0, numShards)),

            context.element().getValue()));

  }

}